ABSTRACT
Objective: During viral infections, antibody production of B cells are critical for protective immunity. It is known that the COVID-19 disease has a milder course in children. It is crucial to evaluate the causes of this situation from a pediatrician’s perspective to determine the treatment goals of the disease. We aimed to examine the flow cytometric changes in B cells and subtypes observed in children diagnosed with the COVID-19 infection. Materials and Methods: This is a prospective cohort study including 22 children aged 0-18 who had been diagnosed with COVID-19. CD19+B cells, CD27-IgD+ naive B, CD21low immature B, CD21lowCD- 38low active B, CD27-IgD- double-negative B, CD27- non-memory B, CD27+ memory B, CD27+IgD- switched memory B, and CD27+IgD+ non-switched memory B cells were studied using flow cytometry. Results: B cells counts decreased as a percentage in the 2-5 years age group and the 10-16 age group as an absolute number. Naive and non-memory B cell frequencies increased in the 5-10 years old and over 16 years old groups. Double negative B cells were normal in all age groups. Non-memory B cells increased in the 5-10 and over 16 years old groups, whereas memory B cells decreased. In all groups, switched memory B cells decreased. Non-switched memory B cell counts were within reference ranges in all groups except for the over 16 years group. Conclusion: Although the decrease in B cell count is associated with the severity of the disease, naive B cell subgroups did not decrease in the pediatric patients included in the study. All groups showed increased switched memory B cell counts, in accordance with the literature. Unlike adults, naive B cells, non-switched memory B cells, and double-negative B cells were normal in children. (English) [ FROM AUTHOR] Amaç: Viral enfeksiyonlar sırasında B hücrelerinin antikor üretimi, koruyucu bağışıklık için kritiktir. Çocuklarda COVID-19 hastalığının daha hafif seyrettiği bilinmektedir. Bu durumun nedenlerini çocuk doktoru gözüyle değerlendirmek, hastalığın tedavi hedeflerini belirlemek açısından çok önemlidir. COVID-19 enfeksiyonu tanısı alan çocuklarda gözlenen B hücre ve alt tiplerinde akım sitometrik değişiklikleri incelemeyi amaçladık. Gereç ve Yöntem: Çalışmamız 0-18 yaş arası COVID-19 teşhisi konulan 22 çocuğu içeren prospektif kohort bir araştırmadır. CD19+B hücreleri, CD27-IgD+ saf B, CD21düşük olgunlaşmamış B, CD21düşükCD38düşük aktif B, CD27-IgD- çift negatif B, CD27- bellek B, CD27+ bellek B, CD27+IgD- dönüşmüş (switched) bellek B, CD27+IgD+ dönüşmemiş (non-switched) bellek B hücreleri akış sitometrisi ile incelenmiştir. Bulgular: B hücre sayısı 2-5 yaş grubunda yüzde olarak, 10-16 yaş grubunda ise mutlak sayı olarak azaldı. 5-10 yaş ve 16 yaş üstü gruplarda naif ve hafıza dışı B hücrelerinin oranları arttı. Çift negatif B hücreleri tüm yaş gruplarında normaldi. Bellek dışı B hücreleri 5-10 yaş arasında ve 16 yaş üzerinde artarken, aynı gruplarda bellek B hücreleri azaldı. Dönüşmüş bellek B hücreleri tüm yaş gruplarında azaldı. Dönüşmemiş bellek B hücreleri, 16 yaşın üzerinde azaldı ve diğer tüm yaş gruplarında normal görünüyordu. Sonuç: B hücre sayısındaki azalma hastalığın şiddeti ile ilişkili olmasına rağmen, çalışmaya dâhil edilen çocuk hastalarımızda naif B hücre alt gruplarında azalma olmadı. Literatüre uygun olarak tüm gruplarda dönüşmüş bellek B hücreleri arttı. Çocuklarda yetişkinlerden farklı olarak naif B hücreleri, dönüşmemiş bellek B hücreleri ve çift negatif B hücreleri normaldi. (Turkish) [ FROM AUTHOR] Copyright of Istanbul Tip Fakültesi Dergisi is the property of Istanbul Tip Fakultesi Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
ABSTRACT
SUMMARY BACKGROUND: The COVID-19 pandemic has affected the entire world, posing a serious threat to human health. T cells play a critical role in the cellular immune response against viral infections. We aimed to reveal the relationship between T cell subsets and disease severity. METHODS: 40 COVID-19 patients were randomly recruited in this cross-sectional study. All cases were confirmed by quantitative RT-PCR. Patients were divided into two equivalent groups, one severe and one nonsevere. Clinical, laboratory and flow cytometric data were obtained from both clinical groups and compared. RESULTS: Lymphocyte subsets, CD4+ and CD8+ T cells, memory CD4+ T cells, memory CD8+ T cells, naive CD4+ T cells, effector memory CD4+ T cells, central memory CD4+ T cells, and CD3+CD4+ CD25+ T cells were significantly lower in severe patients. The naive T cell/CD4 + EM T cell ratio, which is an indicator of the differentiation from naive T cells to memory cells, was relatively reduced in severe disease. Peripheral CD4+CD8+ double-positive T cells were notably lower in severe presentations of the disease (median DP T cells 11.12 µL vs 1.95 µL;p<0.001). CONCLUSIONS: As disease severity increases in COVID-19 infection, the number of T cell subsets decreases significantly. Suppression of differentiation from naive T cells to effector memory T cells is the result of severe impairment in adaptive immune functions. Peripheral CD4+CD8+ double-positive T cells were significantly reduced in severe disease presentations and may be a useful marker to predict disease severity. RESUMO OBJETIVO: A pandemia de COVID-19 tem afetado o mundo todo, constituindo uma ameaça grave para a saúde humana. As células T desempenham um papel crítico na imunidade celular contra infecções virais. Procuramos desvendar a relação entre sub grupos de células T e a severidade da doença. MÉTODOS: Um total de 40 pacientes com COVID-19 foram aleatoriamente recrutados para o presente estudo transversal. Todos os casos foram confirmados por RT-PCR quantitativo. Os pacientes foram divididos em dois grupos equivalentes, um grave e um não-grave. Os dados da avaliação clínica, laboratorial e da citometria de fluxo foram obtidos para ambos os grupos e comparados. RESULTADOS: Os subconjuntos de linfócitos, células T CD4+ e CD8+, células T de memória CD4+, células T de memória CD8+, células T CD4+ virgens, células T efetoras CD4+, células T de memória central CD4+ e células T CD3+ CD4+ CD25+ estavam significativamente mais baixas nos pacientes graves. A razão células T virgens/células T efetoras TCD4+, que é um indicador da diferenciação entre células T virgens e células de memória, estava relativamente reduzida em casos graves da doença. As células T duplo-positivas CD4+CD8+ periféricas estavam notavelmente mais baixas em casos graves da doença (mediana das células T DP: 11,12 µL vs. 1,95 µL;p<0,001). CONCLUSÃO: Conforme aumenta a gravidade da doença nos casos de COVID-19, o número de subconjuntos de células T diminui significativamente. A supressão da diferenciação de células T virgens para células T efetoras é o resultado do comprometimento grave das funções imunológicas adaptativas. As células T duplo-positivas CD4+CD8+ periféricas estavam notavelmente mais baixas em casos graves da doença e podem ser um marcador útil para predizer a severidade da doença.
ABSTRACT
BACKGROUND: The COVID-19 pandemic has affected the entire world, posing a serious threat to human health. T cells play a critical role in the cellular immune response against viral infections. We aimed to reveal the relationship between T cell subsets and disease severity. METHODS: 40 COVID-19 patients were randomly recruited in this cross-sectional study. All cases were confirmed by quantitative RT-PCR. Patients were divided into two equivalent groups, one severe and one nonsevere. Clinical, laboratory and flow cytometric data were obtained from both clinical groups and compared. RESULTS: Lymphocyte subsets, CD4+ and CD8+ T cells, memory CD4+ T cells, memory CD8+ T cells, naive CD4+ T cells, effector memory CD4+ T cells, central memory CD4+ T cells, and CD3+CD4+ CD25+ T cells were significantly lower in severe patients. The naive T cell/CD4 + EM T cell ratio, which is an indicator of the differentiation from naive T cells to memory cells, was relatively reduced in severe disease. Peripheral CD4+CD8+ double-positive T cells were notably lower in severe presentations of the disease (median DP T cells 11.12 µL vs 1.95 µL; p< 0.001). CONCLUSIONS: As disease severity increases in COVID-19 infection, the number of T cell subsets decreases significantly. Suppression of differentiation from naive T cells to effector memory T cells is the result of severe impairment in adaptive immune functions. Peripheral CD4+CD8+ double-positive T cells were significantly reduced in severe disease presentations and may be a useful marker to predict disease severity.